You can find it in basically every laundry room in America, and yet very few people really understand what bleach is and how it works. Here’s an article to make it a little clearer what one of the most commonly used mixtures in the world actually is.

There are two different kinds of bleaches; there’s chlorine bleaches and non-chlorine bleaches. Both of these fall under the category of oxidative agents, meaning that they cause oxidation. Oxidation is a chemical reaction that occurs when bleach comes into contact with certain kinds of stains, germs, organisms, and sometimes (often unfortunately) clothing dyes.

As you’re likely aware, this oxidation tends to come in handy in the laundry room and all around the house. Bleach helps remove stains on clothing and whitens your laundry. It can disinfect linens and surfaces, remove mold and mildew, keep food preparation surfaces safe and clean, disinfect your blender, and maintain hygiene in pools and hot tubs.

This last use is reserved for chlorine bleach in particular. Chlorine bleach is even kept in small amounts in municipal water supplies to help keep public water free of any harmful organisms that might cause disease. Companies sometimes add chlorine bleach to industrial waste water to reduce odor. All together, chlorine bleach in particular is used by a huge amount of industries including the glass, chemical, pharmaceutical, textile, agriculture, paint, and paper industries.

So where did this stuff come from? Bleach was first manufactured in the US in 1913 and used as an institutional disinfectant and a water treatment. Before that, chemicals like borax, ammonia and lye were more commonly used and bleaches using chlorine were difficult to manufacture and thus too expensive to really be worth using.

Because chlorine bleach is the most commonly used kind of bleach, it makes sense to get into the way this bleach is made and what exactly it’s made of. It contains the active ingredient sodium hypochlorite (NaOCl), but non-chlorine bleaches have a lot of different active ingredients that serve different purposes. Hydrogen peroxide, for example, is a bleach that is safe to use on colored clothing as it doesn’t have an active ingredient that will degrade clothing dye.

But how does bleach make the blood stain on your shirt go away? What’s actually happening there on a chemical level? It all has to do with the physics of light. Light is unique because it can be seen as both a particle and a wave. Its particles are called photons and they are said to travel in waves. Not all of these waves are visible to the human eye, and the waves that a particular substance emits has to do with that substance’s chemical makeup. The electrons in some of its chemical bonds are capable of absorbing late at particular wavelengths dependent on the characteristics of the chemical bond itself.

Chlorine bleach is able to oxidize many of these bonds, breaking them and making the substance’s ability to absorb certain kinds of light inert. When this happens, the stain becomes undetectable to the human eye.